One airbrush to rule them all

One airbrush to rule them allModel KIT – G23 – 22 master Airbrush I have a dual action trigger. How do we change from one color to another? Thank you. Also, how do you “know” for example one batch of 13 cupcakes, how much color does one need for that and how do you mix it....

Model KIT – G23 – 22
master
Airbrush

I have a dual action trigger.

How do we change from one color to another? Thank you.
Also, how do you “know” for example one batch of 13 cupcakes, how much color does one need for that and how do you mix it. sorry for being so new. =(